Konnichiwa,
Resonance with the Anode load inductor.
Sayonara
Bas Horneman said:Does anyone know what determines the size of this cap 15uF here?
Resonance with the Anode load inductor.
Sayonara
Hi Thorsten,
I read somewhere that you advise newbies not to build such an amp because 300B's can blow up..
I am planning to build this design into my diyHifiSupply's LD+..
But I really don't understand the problems that could arise with DRD's...could I build it first with a capacitor between d3a and 300b grid to do a smoke test...and if it works remove the cap??
Regards,
Bas
I read somewhere that you advise newbies not to build such an amp because 300B's can blow up..
I am planning to build this design into my diyHifiSupply's LD+..
But I really don't understand the problems that could arise with DRD's...could I build it first with a capacitor between d3a and 300b grid to do a smoke test...and if it works remove the cap??
Regards,
Bas
Konnichiwa,
Actually, the DRD/Monkey principle is safe to build. I refer to split supply direct coupled amplifiers as "potentially 300B Graves".
BTW, I don't think the LD+ has the right supply voltages available, so this may be a non-starter...
Sayonara
Bas Horneman said:I read somewhere that you advise newbies not to build such an amp because 300B's can blow up.
Actually, the DRD/Monkey principle is safe to build. I refer to split supply direct coupled amplifiers as "potentially 300B Graves".
BTW, I don't think the LD+ has the right supply voltages available, so this may be a non-starter...
Sayonara
Yeah..you are right..I thought I could get away with the lower voltages..but...I'll go for d3a choke loaded I think.BTW, I don't think the LD+ has the right supply voltages available, so this may be a non-starter...
Konnichiwa,
Lower supply voltages imply a reduction in power and a complete readjustement of the circuit.
For D3a choke loaded on an LD+ Chassis, look here:
http://www.jogis-roehrenbude.de/Leserbriefe/TH-Loesch-Amp/Th-Loesch-Amp.htm
This has got all the needed stuff, just adjust the input valve cathode resistor to suit the triode wired D3a.
Sayonara
Bas Horneman said:Yeah..you are right..I thought I could get away with the lower voltages.
Lower supply voltages imply a reduction in power and a complete readjustement of the circuit.
For D3a choke loaded on an LD+ Chassis, look here:
http://www.jogis-roehrenbude.de/Leserbriefe/TH-Loesch-Amp/Th-Loesch-Amp.htm
This has got all the needed stuff, just adjust the input valve cathode resistor to suit the triode wired D3a.
Sayonara
Hi all ,
I have built the DRD style amps, currently as 45s.
You can find bits of it over at "Audio round table, group build"
I used Lundel and James outputs, Jacks DRD chokes and the Lady Day style power transformer from DIY HI FI. If I am not mistaken , Thorsten had a big hand in it’s design.
This is a very flexible transformer. Between it’s multiple HV taps, buck boost taps, full or half wave and cap or choke input filters. There is a very wide range of voltages to play with.
Not to mention the clever filament secondary arrangement. Worth a look.
I first breadboarded these as a 45 amp with plans to run 2a3 and 300b as a series of post to ART.
I first set one up with a 6an4 driver , parts bin "fast rectifiers" and some honking big adjustable cathode resistors that could accommodate all 3 tubes. Dialed up the various voltages and had a listen . good. Build another .
Now one of the stated objectives of this project was to try some alternatives to AC heating But with this lash up. There is almost no hum. With my 96db/w speakers, I think what I hear is the diode switching noise. It has to be a very quiet night in N-town before this level of noise is heard.
I have been very busy at work and have not had a lot of time to play. I did toss a pair of 300’s in as a quick and dirty experiment but my heart was not in it. I did not have the time to do it properly and the 45’s were working well for me. I will get back to it as time permits.
In the mean time this is a very worthily configuration to consider…John
I have built the DRD style amps, currently as 45s.
You can find bits of it over at "Audio round table, group build"
I used Lundel and James outputs, Jacks DRD chokes and the Lady Day style power transformer from DIY HI FI. If I am not mistaken , Thorsten had a big hand in it’s design.
This is a very flexible transformer. Between it’s multiple HV taps, buck boost taps, full or half wave and cap or choke input filters. There is a very wide range of voltages to play with.
Not to mention the clever filament secondary arrangement. Worth a look.
I first breadboarded these as a 45 amp with plans to run 2a3 and 300b as a series of post to ART.
I first set one up with a 6an4 driver , parts bin "fast rectifiers" and some honking big adjustable cathode resistors that could accommodate all 3 tubes. Dialed up the various voltages and had a listen . good. Build another .
Now one of the stated objectives of this project was to try some alternatives to AC heating But with this lash up. There is almost no hum. With my 96db/w speakers, I think what I hear is the diode switching noise. It has to be a very quiet night in N-town before this level of noise is heard.
I have been very busy at work and have not had a lot of time to play. I did toss a pair of 300’s in as a quick and dirty experiment but my heart was not in it. I did not have the time to do it properly and the 45’s were working well for me. I will get back to it as time permits.
In the mean time this is a very worthily configuration to consider…John
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